1. Field of the Invention
The present invention relates generally to a cleaning machine and, more specifically, to a dishwashing apparatus and method of use that utilizes a mixture of liquid and granules to clean soiled articles, and includes one or more granule collectors to separate the mixture.
2. Description of Related Art
Dishwashing machines, needed to handle high volume and heavily soiled articles, such as in a commercial setting, are well known in the art. It is common practice to mix small, hard particles, such as granules, with water and detergent to achieve an optimal cleaning mixture that is sprayed under high pressure against articles to be washed. Generally, the machines are equipped with a tank, spraying nozzles, and pumps. The liquid or liquid/granule combination is pumped to the nozzles where it is sprayed against articles to be cleaned. After the articles are cleaned, a separation cycle is necessary in order to remove any leftover residue or granules. Thus, a separation method for the granules is essential.
Many prior art references include machines functioning similarly to the above-described process, utilizing various separation methods. For example, U.S. Pat. No. 4,374,443 to Mosell discloses a cleaning machine that uses a liquid-permeable compartment or cassette which either separates or combines the cleaning liquid and granules. This liquid permeable compartment is located inside a liquid container and connects the bottom of a treatment chamber to the liquid container. The liquid permeable compartment communicates with a pump via a valve-controlled opening. Based upon whether the valve-controlled opening is open or closed, either cleaning liquid alone or a slurry of liquid and granules will be drawn by the pump through a suction chamber which is connected to the liquid container. Once the pump has drawn the liquid or the liquid/granule slurry, the fluid alone or slurry will be sprayed through nozzles located in the treatment chamber against goods to be cleaned. In another patent issued to Mosell (U.S. Pat. No. 4,801,333), a cleaning machine is disclosed that separates granules by using two different levels for liquid and granules. A branch conduit is connected to a bottom outlet and a tank at a position above the surface of a bottom layer of granules below a liquid surface (the granules have a higher density than the liquid). The branch conduit has a float valve at an opening inside the tank and a closure valve between the bottom outlet and the position where the two conduits meet. When the closure valve is opened, the pump will draw from the tank through the bottom conduit, drawing liquid and granules to blast the soiled articles in a treatment chamber. When the closure valve is closed, the pump will draw liquid from the tank through the branch conduit and liquid only will be supplied for rinsing the cleaned articles.
U.S. Pat. No. 5,468,175 to Nilxc3xa9n discloses another way of separating granules in a cleaning machine. The granules are separated by a dividing wall with a pivoting portion at the wall base. The dividing wall separates the tank into two chambers, one with liquid only and the other with liquid and granules. The pivoting arm seals against the tank to prevent granules from passing when closed, and when opened allows granules to pass along with the liquid into the pump, to be recirculated through the system. A different type of separation system was also disclosed by Nilxc3xa9n in U.S. Pat. No. 5,601,480. In this design, separation of granules is done by a separation plate that extends some distance up from the bottom. This separates the tank into two chambers, a small, liquid only chamber and a larger liquid and granule chamber. A second perforated plate may also be attached to the top of the liquid chamber to insure that no granules pass through. Two pumps are required for this system, one connected to each chamber. Depending on the desired make-up of the substance to be sprayed (liquid only or a liquid/granule mixture), each pump is turned on independently.
In U.S. Pat. No. 5,667,431 to Mortin, yet another type of separation device is disclosed. The separation in this patent is done by separating the holding tank into two sections. The first section has a strainer at the bottom that allows the granules to pass into a conduit which is attached to a pump. If water gets too high in the first section it will spill over to the other section. Because the density of the granules is greater than the density of water, the overflow will theoretically contain liquid only. This second, liquid only section also has a conduit which is attached to a pump. Both pumps carry the liquid or liquid/granule mixture to a nozzle arrangement where they are sprayed against the articles to be cleaned. Alternatively, if the density of the granules is less than the water, a separate embodiment contemplates a system where the passage is at the bottom of the tank and the supply means is located in the upper portion.
Finally, U.S. Pat. No. 5,735,730 to Jonemo et al. discloses a dishwasher that uses a valve separation device to separate the granules from the liquid. The granule valve has a socket open at each end, and is associated with a bottom outlet. The socket is guided for vertical displacement between the upper position, with an opening at the lower end of the socket for drawing liquid with granules entrained therein by a pump from a treatment space at a lower level, and a lower position with the opening at the lower end of the socket closed for drawing liquid only by the pump from a higher level at the upper end of the socket. A projecting circumferential flange is provided on the socket below the upper end of the socket forming together with a cap that is located over the socket, a seal for preventing granules from being withdrawn along with the liquid.
While the prior art cleaning machines separate granules from liquids in a variety of ways, all are very difficult to clean at the end of a working shift. This can be largely attributed to the fact that the granules remain in the tank after the cleaning cycle, gravitating around the separation devices. Thus, cleaning the bottom of the tank becomes laborious. In view of the increasing demands from users for improved hygienic properties in the cleaning machines, a need exists to develop a cleaning machine which will collect the granules in an efficient manner so they can be removed for cleaning of the machine. In addition, removal of the granules is advantageous because the amount of granules can be monitored so that granules can be added when necessary to ensure that articles are consistently subjected to optimal cleaning conditions.
It is therefore an object of this invention to provide a granule dishwashing apparatus that is easy to clean at the end of a wash cycle.
It is another object of this invention to provide a granule dishwashing apparatus that utilizes granule collectors to separate granules from liquid.
It is still a further object of this invention to provide granule collectors in a granule dishwashing apparatus that are easy to install and remove.
It is yet another object of this invention to provide a granule dishwashing apparatus that is easy to use and inexpensive to produce.
In accordance with the teachings of the present invention, a granule dishwashing apparatus with easily removable granule collectors and method of use is provided. The present invention encompasses a complete system for heavy-duty cleaning of articles, which is useful, for example, in a commercial environment. This system includes a treatment chamber for cleaning soiled articles, nozzles to spray liquid or a liquid/granule mixture against the articles, a pump or pumps to carry the liquid or liquid/granule mixture through the machine, and granule collectors to separate the granules from the liquid and to provide an easy way to remove the granules from the apparatus.
In a first embodiment of the invention, the granule dishwashing apparatus consists of one pump and piping system along with two granule collectors side-by-side, cleaning goods by using either a cleaning liquid entrained with granules (xe2x80x9cthe slurryxe2x80x9d) or liquid only. This embodiment also includes a treatment chamber in which goods to be cleaned are stored in a washing rack. Nozzles in the treatment chamber spray a cleaning agent against the articles in the washing rack. The cleaning agent, which is pumped from a collection tank below the treatment chamber, may be either a cleaning fluid only or the slurry.
When the cleaning agent has impacted the goods, it forms a return flow which travels downward from the treatment chamber and is received by a tank below the chamber. The tank and treatment chamber form a single contiguous space within the dishwashing machine. Granule collectors are positioned side-by-side either in the tank or in the treatment chamber where they can receive the return flow. Assuming that the cleaning agent consists of the slurry, the granule collectors can either collect and separate the granules from the cleaning fluid or allow the granules to travel unimpeded with the cleaning liquid. Once the return flow has passed the granule collectors, it enters a conduit connected to the bottom of the tank. A pump draws the return flow through the conduit and pumps it back to the nozzles to be sprayed against the goods once again.
The granule collectors are discrete units, separate from the walls of the treatment chamber and the tank, and are removably and rotatably mounted in the machine. The granule collectors are coupled to actuators located outside of the machine. The actuators facilitate the two modes of operation for the granule collectors: collection and release. In the collection mode, the granule collectors are positioned by the actuators to xe2x80x9ccatchxe2x80x9d the return flow in order to separate and collect the granules from the slurry. By catching the granules, the collectors allow the cleaning liquid alone to pass to the bottom of the tank and to be drawn by the pump and ejected through the nozzles. When the collectors are in the release mode, they do not catch the return flow. Thus, the return flow travels directly to the bottom of the tank and can be drawn by the pump through the conduit. In addition, in the release mode, granules previously collected by the collectors will be reintroduced to the return flow.
The granule collectors of the dishwashing machine allow the machine to be operated using a liquid only cleaning agent. This is advantageous for several reasons. First, for lightly soiled goods, a liquid only cycle may be desired. The collectors ensure that only liquid is ejected by the nozzles and circulated through the system. Second, at the end of the day, it is highly desirable to clean the dishwashing machine. Collection of the granules by way of the granule collectors greatly facilitates the cleaning task. Third, the granule collectors enable the operator to quickly and easily monitor the amount of granules remaining in the cleaning machine. A visual inspection of the granules captured in the collectors enables the operator to readily determine if there are sufficient granules or whether more granules should be added to the machine. Because the granule collectors are removable, this task can be accomplished quickly and efficiently.
In the preferred embodiment, the granule collector is formed of a basket having a bottom, side walls and end walls. Some or all of the walls of the collectors may be perforated. If a collector is in the collection mode and its walls are perforated, the liquid in the return flow passes through the perforations in the walls. Alternatively, if the walls are not perforated, the liquid initially collects in the collector, but when the volume of the liquid exceeds that of the collector, the liquid simply overflows the rims of the collector. The release mode for the collectors involves the rotation of the granule collectors onto their sides so that the return flow from the treatment chamber mostly bypasses them and travels unimpeded to the conduit at the bottom of the tank.
A second embodiment of the invention is also a cleaning machine that cleans goods by using a cleaning agent, which may be either a cleaning liquid entrained with granules (xe2x80x9ca slurryxe2x80x9d) or fluid only. However, in the second embodiment, there are two pumps utilized and the granule collection process involves only one collector. Moreover, the second machine can be smaller, for less voluminous uses, than the first. The second embodiment, like the first, includes a treatment chamber in which goods to be cleaned are stored in a washing rack. Nozzles in the treatment chamber spray the cleaning agent against the goods in the washing rack, and the cleaning agent is stored in and pumped from a collection tank located below the treatment chamber. When the cleaning agent has impacted the goods, it forms a return flow which travels downward from the treatment chamber and is received by the collection tank. The tank and treatment chamber form a single contiguous space within the dishwashing machine.
Assuming that the return flow is a slurry of fluid and granules, this embodiment utilizes a removable, basket-like granule collector to collect and separate granules from the cleaning fluid. During the machine""s operation, however, the collector is stationary; that is, the device is always in a granule collection mode. The collector of the machine is located near the bottom of the collection tank and has perforated walls that permit liquid in the return flow to pass through them. Because the granule collector sits above the bottom of the tank, the collector segregates a portion of the tank below it. The portion of the collection tank below the granule collector contains cleaning fluid only and is thus granule-free. The bottom of the collector has a hole through which a primary conduit extends upwards into the collector and a deflector is located above this hole. When the collector is correctly positioned in the collection tank, the primary conduit extends upward through the hole in the bottom of the collector and terminates below the deflector. The deflector prevents granules in the return flow from falling directly into the primary conduit and displaces them to the bottom or sides of the granule collector.
The primary conduit is connected to a primary pump which in turn is connected to a primary set of nozzles in the treatment chamber. When the goods are to be cleaned with a slurry, the primary pump is activated, drawing granules from the granule collector together with cleaning liquid through the primary conduit in the tank. The primary pump discharges this slurry against the goods in the treatment chamber. The collector catches the return flow, filtering and collecting granules from the flow, and permitting liquid to pass through the perforations in its walls and collect in the tank.
When cleaning fluid alone is to be discharged against the goods, the primary pump system is disabled, and a secondary pump system which includes a secondary set of nozzles, pump and conduit is employed. A secondary conduit is connected to the portion of the tank below the granule collector. A secondary pump is connected to the secondary conduit as well as to a secondary set of nozzles in the treatment chamber. When the secondary pump is activated, it withdraws liquid only from the tank below the granule collector and sprays the fluid through the secondary nozzles against the goods stored in the treatment chamber.
A more complete understanding of the granule dishwashing technology of the present invention will be afforded to those skilled in the art, as well as a realization of additional advantages and objects thereof, by a consideration of the following detailed description of the preferred embodiments. Reference will be made to the appended sheets of drawings that will first be described briefly.